Supported zinc-calcium complex as well as preparation method and application thereof

Abstract

The invention provides a supported zinc-calcium complex as well as a preparation method and application thereof. By adopting the one-step leaching method of the carbide slag and the zinc oxide ore, ammonia released when the carbide slag is dissolved under the action of ammonium chloride is fully utilized, and zinc ions in the zinc oxide ore are leached by utilizing the ammonia component, so that the situation that ammonia water is additionally added when the zinc oxide ore is leached can be avoided, and the preparation process is simplified; meanwhile, zinc and calcium refined clear liquid obtained through leaching is subjected to a one-step pyrolysis and carbonization method, the interaction between free ammonia generated during pyrolysis of the zinc-ammonia complex and ammonia consumed during carbonization of soluble calcium is fully utilized, additional addition of ammonia during calcium carbonization is avoided, and the energy consumption of ammonia distillation of the zinc-ammonia complex is reduced; the preparation method is simple in technological process, and the cost of the calcium carbonate carrier and ammonia is greatly reduced; meanwhile, the leaching liquid ammonium chloride and the carbon dioxide can be recycled, so that the input cost of the leaching liquid and the carbon dioxide is reduced, and the emission of nitrogen-containing waste liquid is reduced.

Description

Technical Field

[0001] This invention belongs to the technical field of zinc-calcium complexes, specifically relating to a supported zinc-calcium complex, its preparation method, and its applications. Background Technology

[0002] Zinc oxide (ZnO) is a commonly used chemical additive with wide applications in industries such as rubber, plastics, aquaculture, and batteries. For example, zinc oxide plays an indispensable role as a vulcanization activator in promoting the cross-linking of rubber vulcanization. However, as a soluble zinc compound, ZnO, a rubber vulcanization aid, has a significant toxic effect on the environment. Zinc ions are released from rubber into the environment during both the production and recycling / landfill processes. Therefore, excessive use of zinc oxide can lead to serious zinc pollution problems, severely impacting air, water, and soil. In recent years, domestic and international policies and regulations have been introduced to gradually strengthen restrictions on zinc usage in order to reduce the environmental pollution caused by zinc-containing products. At the same time, the increasing demand for zinc oxide, coupled with drastic fluctuations in international zinc prices, has placed greater cost pressure on downstream rubber manufacturers. Therefore, developing new zinc oxide preparation processes to enhance the activity of zinc oxide in rubber products and reduce zinc usage is highly effective in reducing environmental pollution and alleviating cost pressures.

[0003] Currently, the mainstream view holds that the mechanism of zinc oxide in the rubber vulcanization process is that zinc oxide participates in the rubber vulcanization reaction as a vulcanizing aid, which is essentially an interfacial reaction. That is, only the zinc ions in the surface zinc oxide can play a role, while the zinc ions inside the zinc oxide particles remain within the zinc oxide lattice, resulting in significant waste of zinc oxide. To reduce the waste of zinc oxide inside the particles, a feasible method is to construct a coated structure with relatively inexpensive inert materials such as calcium carbonate, silica, and carbon black as the core and nano-zinc oxide as the shell. Moreover, compared to directly using nano-zinc oxide, this supported core-shell structure not only avoids the aggregation of nano-zinc oxide itself and fully utilizes the vulcanizing aid effect of the surface zinc oxide, but also effectively reduces the amount of zinc used, completely achieving the goal of zinc reduction and high efficiency.

[0004] According to existing reports, coated supported zinc oxide typically involves adding soluble zinc salts and precipitants sequentially to a slurry of calcium carbonate or other powders. This causes zinc to deposit on a carrier surface as zinc hydroxide (Zn(OH)₂) or basic zinc carbonate (ZnCO₃·2Zn(OH)₂·2H₂O). High-temperature calcination then pyrolyzes the precipitated zinc into nano-zinc oxide, achieving the loading and coating of zinc oxide on the carrier surface. However, these methods all use relatively expensive soluble zinc salts, such as zinc sulfate, zinc nitrate, and zinc acetate, as the zinc source. This leads to high overall production costs, and the zinc precipitation process is difficult to control, resulting in uneven particle size of the zinc oxide shell and affecting the quality of the supported zinc oxide. In contrast to these surface deposition methods, the zinc oxide-ammonium sulfate method achieves controllable deposition of zinc species on a carrier by controlling the complexation and dissociation of ammonia molecules at zinc ion centers. The advantage of this preparation process is that the zinc source can be relatively inexpensive secondary zinc oxide or industrial zinc-containing waste liquid. However, in the zinc leaching process, a large amount of ammonia and ammonium bicarbonate solution is required to improve leaching efficiency, which also increases production costs. At the same time, the ammonia stripping and filtration processes also discharge a large amount of nitrogenous ammonia wastewater, causing environmental pollution. Summary of the Invention

[0005] To address the shortcomings of existing supported zinc-calcium composites, such as high zinc source cost, large consumption of ammonium leaching solution (the ammonium leaching solution refers to the leaching solution obtained by the zinc oxide-ammonium leaching method, whose main components are ammonium salts (ammonium chloride, ammonium carbonate, etc.) and ammonia water, also known as ammonia-carbon ammonium leaching solution), significant environmental pollution from waste liquid generated during the preparation process, and high preparation cost, this invention provides a supported zinc-calcium composite, its preparation method, and its applications. The supported zinc-calcium composite uses calcium carbide slag and zinc oxide ore as calcium and zinc sources, respectively, to prepare a zinc-calcium mixed solution through a one-step leaching method. Then, it undergoes impurity removal, pyrolysis carbonization, and calcination processes to construct a nanoscale supported zinc-calcium composite. The preparation method is characterized by high efficiency, reduced zinc content, and lower cost.

[0006] The objective of this invention is achieved through the following technical solution: A method for preparing a supported zinc-calcium complex, the method comprising the following steps: (1) Add ammonium chloride solution to the mixture of calcium carbide slag and zinc oxide ore, react, filter, and obtain zinc and calcium leaching solution; (2) Add zinc powder to the zinc and calcium leaching solution, react, filter, and obtain a refined zinc and calcium solution; (3) Add crystal form control agent to zinc and calcium refined clear liquid, then pass carbon dioxide gas flow, and at the same time pyrolyze and carbonize the mixed slurry, filter, dry, and obtain pyrolyze and carbonize products. (4) The pyrolysis carbonization products are roasted to prepare the supported zinc-calcium composite.

[0007] According to an embodiment of the present invention, in step (1), the temperature of the reaction is 20-40°C; the reaction time is 2-12 hours, such as 3-6 hours; and the reaction is carried out under stirring conditions.

[0008] According to an embodiment of the present invention, in step (1), the calcium carbide slag serves as a calcium source. The calcium carbide slag is an industrial solid waste generated during the production of acetylene from calcium carbide, and its main component is Ca(OH)2 (exemplarily, the mass content of Ca(OH)2 is above 80wt%, such as 80-95wt%), while also containing small amounts of metal oxide impurities such as magnesium, aluminum, and iron.

[0009] According to an embodiment of the present invention, in step (1), the zinc oxide ore serves as the zinc source. The zinc oxide ore is a low-grade zinc oxide ore whose main component is ZnO, with a zinc oxide content of more than 30 wt%, and also contains impurities such as manganese, lead, iron, and cadmium oxides.

[0010] According to an embodiment of the present invention, in step (1), in order to ensure that the calcium ions in the carbide slag and the zinc ions in the zinc oxide ore are dissolved as completely as possible, it is preferable to crush the carbide slag and zinc oxide ore raw materials, for example, to obtain carbide slag and zinc oxide ore with a particle size of less than 10 mesh.

[0011] According to an embodiment of the present invention, in step (1), the feeding ratio of the calcium carbide slag and zinc oxide ore satisfies the following: the atomic ratio of zinc atoms to calcium atoms is 1:(0.5-3), for example, 1:0.5, 1:0.6, 1:0.8, 1:0.9, 1:1, 1:1.2, 1:1.3, 1:1.5, 1:1.6, 1:1.8, 1:2, 1:2.2, 1:2.4, 1:2.5, 1:2.6, 1:2.8, or 1:3. Studies have found that if the atomic ratio of calcium atoms is too low (e.g., the proportion of calcium atoms is less than 0.5), the ammonia (NH3) produced during the leaching process will be insufficient to fully dissolve the zinc oxide ore; if the atomic ratio of zinc atoms is too low (e.g., the proportion of calcium atoms is higher than 3), the zinc oxide content in the finally prepared supported zinc-calcium composite will be too low, failing to form a completely coated structure on the surface of the calcium carbonate carrier, resulting in low activity of the supported zinc-calcium composite.

[0012] According to an embodiment of the present invention, in step (1), the feeding ratio of the calcium carbide slag and the ammonium chloride solution satisfies the following: the molar ratio of calcium to ammonium chloride is 1:(3-8), for example, 1:3, 1:3.5, 1:4, 1:4.5, 1:5, 1:5.5, 1:6, 1:6.5, 1:7, 1:7.5, or 1:8. Studies have found that if the molar ratio of ammonium chloride is too low (e.g., below 1:3), it is insufficient to fully dissolve the calcium carbide slag and zinc oxide ore; if the molar ratio of ammonium chloride is too high (e.g., above 1:8), it results in an excess of ammonium chloride, leading to increased preparation costs.

[0013] According to an embodiment of the present invention, in step (1), the ammonium chloride solution is preferably an aqueous solution of ammonium chloride. The concentration of the ammonium chloride solution is 1-5 mol / L, such as 1.5-3 mol / L, such as 1.5 mol / L, 2 mol / L, 2.5 mol / L, or 3 mol / L. The ammonium chloride solution serves as a leaching solution to achieve the dissolution of calcium ions from carbide slag and zinc ions from zinc oxide ore.

[0014] According to an embodiment of the present invention, in step (1), the main component of the carbide slag is Ca(OH)2, which is a strong alkali; ammonium chloride is a weak base-strong acid salt, and its solution is acidic; the two will undergo an acid-base reaction in the liquid phase, promoting the dissolution of the carbide slag and generating soluble calcium ions (Ca2+, Ca ... 2+ The specific reaction equation is: Ca(OH)2 + 2NH4Cl → CaCl2 + 2NH3 + 2H2O.

[0015] According to an embodiment of the present invention, in step (1), the NH3 and excess NH4Cl generated during the dissolution of the carbide slag also promote the dissolution of ZnO in the zinc oxide ore, generating a soluble zinc ammonia complex ([Zn(NH3)2]). i Cl2). The specific reaction equation is: ZnO + ( i -2)NH3 + 2NH4Cl → [Zn(NH3) i Cl2 + H2O; where, i = 2, 3 or 4.

[0016] According to an embodiment of the present invention, in step (1), in addition to the dissolution reaction of calcium carbide slag and zinc oxide ore, the following side reactions are also involved in the reaction process; the specific reaction equations are as follows: j CaCl2+ M2S j → j CaS↓ + 2MCl j ; j CaCl2 + M2(SO4) j → jCaSO4↓ + 2MCl j M j+ + ( i - j NH3+ j NH4Cl → [M(NH3) i Cl j + H2O; where M is other impurity metals that may exist in carbide slag and zinc oxide ore, such as Mg, Al, Fe, Pb, Cd, Cu, etc. j = 2 or 3.

[0017] According to an embodiment of the present invention, in step (1), after the reaction is completed, the mixed slurry is filtered and the filtrate is collected to obtain zinc and calcium leaching solution. The filtration step can remove some insoluble impurity components (such as metal compounds such as Sb and Bi) and calcium salt precipitates (CaS and CaSO4) generated during the reaction in step (1).

[0018] According to an embodiment of the present invention, in step (1), the leaching residue collected after filtration may still contain some undissolved calcium and zinc components. In order to improve the utilization rate of raw materials, leaching can be carried out again, that is, ammonium chloride solution is added to the leaching residue, reaction is carried out, filtration is performed, the filtrate is collected, and mixed with the zinc and calcium leaching solution obtained in the first leaching.

[0019] According to an embodiment of the present invention, in step (1), the zinc and calcium leaching solution includes Zn 2+ Ca 2+ and M j+ , j = 2 or 3, where M represents other impurity metals that may be present in the calcium carbide slag and zinc oxide ore, such as Fe, Pb, Cd, Cu, Al, Mg, etc. For example, the zinc and calcium leaching solution includes NH4Cl and [Zn(NH3)2]. i Cl2, MCl j [M(NH3)] i Cl j And CaCl2.

[0020] According to an embodiment of the present invention, in step (1), the zinc and calcium leaching solution contains Zn 2+ The concentration is 0.2-1 mol / L, for example, 0.2 mol / L, 0.3 mol / L, 0.4 mol / L, 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L or 1 mol / L.

[0021] According to an embodiment of the present invention, in step (1), the zinc and calcium leaching solution contains Ca... 2+The concentration is 0.2-1 mol / L, for example, 0.2 mol / L, 0.3 mol / L, 0.4 mol / L, 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L or 1 mol / L.

[0022] According to an embodiment of the present invention, in step (1), M in the zinc and calcium leaching solution j+ The concentration is 0.01-0.1 mol / L, for example, 0.01 mol / L, 0.02 mol / L, 0.03 mol / L, 0.04 mol / L, 0.05 mol / L, 0.06 mol / L, 0.07 mol / L, 0.08 mol / L, 0.09 mol / L or 0.1 mol / L.

[0023] According to an embodiment of the present invention, in step (2), the temperature of the reaction is 30-50ºC; the reaction time is 1-6 hours, such as 2-3 hours; and the reaction is carried out under stirring conditions.

[0024] According to an embodiment of the present invention, in step (2), the zinc powder is used to remove other metallic impurities (such as MCl) from the zinc and calcium leaching solution of step (1). j [M(NH3)] i Cl j It can be reduced to a metallic element, and the amount added should be excessive.

[0025] According to an embodiment of the present invention, in step (2), the zinc powder will remove other metallic impurities (such as MCl) from the zinc and calcium leaching solution of step (1). j [M(NH3)] i Cl j The reduction to a metallic element occurs through the following reaction equation: j Zn +2MCl j → j ZnCl2+ 2M; j Zn + 2[M(NH3) i Cl j → j [Zn(NH3) i Cl2+ 2M; M represents other impurity metals that may be present in carbide slag and zinc oxide ore, such as Fe, Pb, Cd, Cu, Al, Mg, etc. j = 2 or 3.

[0026] According to an embodiment of the present invention, in step (2), after the reaction is completed, the mixed slurry is filtered, and the filtrate is collected to obtain a refined zinc and calcium solution. The filtration step removes excess zinc powder and displaced impurity elemental M.

[0027] According to an embodiment of the present invention, in step (2), the zinc and calcium refined solution includes Zn 2+ Ca 2+ and M j+ , j = 2 or 3, where M represents other impurity metals that may be present in the calcium carbide slag and zinc oxide ore, such as Al, Mg, etc. For example, the zinc and calcium refined solution includes NH4Cl and [Zn(NH3)2]. i Cl2, MCl j [M(NH3)] i Cl j And CaCl2.

[0028] According to an embodiment of the present invention, in step (2), the zinc and calcium refined solution contains Zn 2+ The concentration is 0.2-1 mol / L, for example, 0.2 mol / L, 0.3 mol / L, 0.4 mol / L, 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L or 1 mol / L.

[0029] According to an embodiment of the present invention, in step (2), the zinc and calcium refined solution contains Ca... 2+ The concentration is 0.2-1 mol / L, for example, 0.2 mol / L, 0.3 mol / L, 0.4 mol / L, 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L or 1 mol / L.

[0030] According to an embodiment of the present invention, in step (2), M in the zinc and calcium refined solution j+ The concentration is 0.001-0.01 mol / L, for example, 0.001 mol / L, 0.002 mol / L, 0.003 mol / L, 0.004 mol / L, 0.005 mol / L, 0.006 mol / L, 0.007 mol / L, 0.008 mol / L, 0.009 mol / L or 0.01 mol / L.

[0031] According to an embodiment of the present invention, in step (3), the crystal form control agent is selected from at least one of dodecyltrimethylammonium bromide, polyethylene glycol, and sodium polyacrylate. The purpose of adding the crystal form control agent is to control the nucleation and grain formation of CaCO3 in the carbonization step, and to prevent the formation of too many large-sized CaCO3 particles, which would affect the loading and dispersion of ZnO during the pyrolysis roasting process.

[0032] According to an embodiment of the present invention, in step (3), the mass ratio of the crystal form control agent to the carbide slag is 2-5:100, for example, 2:100, 2.5:100, 3:100, 3.5:100, 4:100, 4.5:100 or 5:100.

[0033] According to an embodiment of the present invention, in step (3), the carbon dioxide gas flow is preferably a mixed gas flow of carbon dioxide and air, wherein the volume concentration of carbon dioxide is 6-10 vol%, for example, 6 vol%, 7 vol%, 8 vol%, 9 vol%, or 10 vol%. Studies have found that if the concentration of carbon dioxide introduced during pyrolysis carbonization is too low (volume concentration of carbon dioxide < 6 vol%), carbonization will be insufficient; if the concentration of carbon dioxide introduced during pyrolysis carbonization is too high (volume concentration of carbon dioxide > 10 vol%), the precipitated calcium particles generated by carbonization will be too large, resulting in poor dispersibility of the zinc-calcium complex.

[0034] According to an embodiment of the present invention, in step (3), the flow rate of the carbon dioxide gas stream introduced into each liter of zinc and calcium refined solution is 0.5-3 L / min, for example, 0.5 L / min, 1 L / min, 1.5 L / min, 2 L / min, 2.5 L / min or 3 L / min.

[0035] According to an embodiment of the present invention, in step (3), the temperature of the pyrolysis carbonization treatment is 60-90ºC, for example, 60℃, 65℃, 70℃, 75℃, 80℃, 85℃ or 90℃; the time of the pyrolysis carbonization treatment is 6-10 hours, for example, 6 hours, 7 hours, 8 hours, 9 hours or 10 hours. The pyrolysis carbonization treatment is carried out under stirring conditions.

[0036] According to an embodiment of the present invention, in step (3), during the pyrolysis and carbonization process, the zinc-ammonia complex in the zinc and calcium refined solution will promote the dissociation of the complexed ammonia under pyrolysis, producing non-complexed zinc ions and free ammonia. The specific reaction equation is: [Zn(NH3)] i Cl2→ ZnCl2+ i NH3.

[0037] According to an embodiment of the present invention, in step (3), during the pyrolysis and carbonization process, the generated free ammonia and continuously dissolved CO2 not only transform into carbon-ammonia compounds, but also promote the carbonization and precipitation of soluble calcium ions, generating nano-calcium carbonate (CaCO3); the specific reaction equations are: 2NH3 + CO2 + H2O → (NH4)2CO3; CaCl2 + 2NH3 + CO2 + H2O → CaCO3↓ + 2NH4Cl. Furthermore, as the free ammonia in the system is consumed, the pyrolysis of the zinc-ammonia complex is further promoted, generating more non-complexed zinc ions; the specific reaction equation is: [Zn(NH3)2CO3 + CO2 + H2O → CaCO3↓ + 2NH4Cl]. i Cl2→ ZnCl2+ i NH3.

[0038] According to an embodiment of the present invention, in step (3), during the pyrolysis carbonization process, after the soluble calcium ions are completely carbonized and precipitated, the continuously dissolved CO2 causes the non-complexed zinc ions generated by pyrolysis to precipitate and deposit on the surface of nano-calcium carbonate (CaCO3) in the form of basic zinc carbonate (ZnCO3·2Zn(OH)2·2H2O). The specific reaction equation is: 3ZnCl2 + 3(NH4)2CO3 + 4H2O → ZnCO3·2Zn(OH)2·2H2O↓ + 2CO2↑ + 6NH4Cl.

[0039] According to the embodiment of the present invention, in step (3), after the pyrolysis carbonization treatment is completed, in order to ensure that the reaction is fully carried out, stirring is continued for 20-60 minutes for aging treatment; that is, after stopping the introduction of carbon dioxide, stirring is continued for 20-60 minutes for aging treatment.

[0040] According to an embodiment of the present invention, in step (3), after the pyrolysis carbonization treatment is completed, the mixed slurry is filtered, the solid components are collected, and the solid components are washed with deionized water until there are no chloride ions in the filtrate.

[0041] According to an embodiment of the present invention, in step (3), after the pyrolysis carbonization treatment is completed, the mixed slurry is filtered to collect the liquid component, which contains a large amount of NH4Cl. This liquid component can be concentrated to produce a high-concentration ammonium chloride solution (such as an ammonium chloride solution with a concentration of 1-5 mol / L), which is then reused in step (1) as a leaching solution. This not only reduces the input cost of raw materials but also reduces the discharge of nitrogen-containing wastewater.

[0042] According to an embodiment of the present invention, in step (3), the drying temperature is 80-100ºC; the drying time is 4-8 hours.

[0043] According to an embodiment of the present invention, in step (4), the calcination process is carried out in a muffle furnace. The temperature of the calcination process is 300-500ºC, more preferably 350-400ºC. The calcination process lasts for 4-10 hours.

[0044] According to an embodiment of the present invention, in step (4), calcium carbonate does not decompose during the calcination process, but basic zinc carbonate does decompose, releasing carbon dioxide, and simultaneously generating highly dispersed zinc oxide on the surface of nano-calcium carbonate. The specific reaction equation is: ZnCO3·2Zn(OH)2·2H2O → 3ZnO + CO2↑ + 3H2O↑.

[0045] According to an embodiment of the present invention, in step (4), the gas released during the roasting process contains CO2, which can be captured or enriched to form a high-concentration mixture of carbon dioxide and air, which can be reused in the pyrolysis carbonization process of step (3) to reduce the input of raw materials and reduce the emission of carbon dioxide.

[0046] The present invention also provides a supported zinc-calcium composite prepared by the above method.

[0047] According to an embodiment of the present invention, the supported zinc-calcium composite comprises zinc oxide and calcium carbonate, wherein the zinc oxide is coated on the surface of the calcium carbonate, and the supported zinc-calcium composite has a core-shell structure, wherein the core is calcium carbonate and the shell is zinc oxide.

[0048] According to an embodiment of the present invention, the average particle size of the supported zinc-calcium composite is 200-600 nm, for example, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm, 500 nm, 550 nm or 600 nm.

[0049] According to an embodiment of the present invention, the specific surface area of ​​the supported zinc-calcium composite is 40-120 m². 2 / g, for example, 40m 2 / g, 50m 2 / g、60m 2 / g、70m 2 / g、80m 2 / g、90m 2 / g, 100m 2 / g、110m 2 / g or 120m 2 / g.

[0050] According to an embodiment of the present invention, the thickness of the shell layer is 10-20 nm.

[0051] According to an embodiment of the present invention, the calcium carbonate accounts for 30-70 wt% of the total mass of the supported zinc-calcium composite, for example, 30 wt%, 35 wt%, 40 wt%, 45 wt%, 50 wt%, 55 wt%, 60 wt%, 65 wt%, or 70 wt%.

[0052] According to an embodiment of the present invention, the zinc oxide accounts for 30-70 wt% of the total mass of the supported zinc-calcium composite, for example, 30 wt%, 35 wt%, 40 wt%, 45 wt%, 50 wt%, 55 wt%, 60 wt%, 65 wt%, or 70 wt%.

[0053] The present invention also provides the use of the above-mentioned supported zinc-calcium composite as a vulcanization aid in the field of rubber processing.

[0054] The present invention also provides a rubber vulcanization method, the method comprising using the above-mentioned supported zinc-calcium composite as a vulcanization aid.

[0055] The beneficial effects of this invention are: This invention provides a supported zinc-calcium composite, its preparation method, and its applications. The method uses industrial solid waste carbide slag and inexpensive zinc oxide ore as raw materials, employing a one-step leaching process to prepare a highly active supported zinc-calcium composite. Specifically, this invention utilizes a one-step leaching method between carbide slag and zinc oxide ore, fully leveraging the ammonia released when the carbide slag dissolves under the action of ammonium chloride. This ammonia component is used to leach zinc ions from the zinc oxide ore, avoiding the need for additional ammonia during leaching and simplifying the preparation process. Simultaneously, the refined zinc and calcium solution obtained from the leaching is processed using a one-step pyrolysis and carbonization method, fully utilizing the interaction between the free ammonia generated during the pyrolysis of the zinc-ammonia complex and the ammonia consumed during the carbonization of soluble calcium. This avoids the need for additional ammonia during calcium carbonization and reduces the energy consumption of ammonia stripping from the zinc-ammonia complex. The preparation method has a simple process flow, significantly reducing the cost of calcium carbonate carrier and ammonia. Furthermore, the ammonium chloride and carbon dioxide in the leaching solution can be recycled and reused, reducing the input costs of the leaching solution and carbon dioxide, and decreasing the discharge of nitrogen-containing wastewater. Attached Figure Description

[0056] Figure 1 This is a flowchart illustrating the preparation process of the supported zinc-calcium composite according to a preferred embodiment of the present invention; Figure 2 The XRD diffraction pattern of the supported zinc-calcium composite product prepared in Example 2 of this invention; Figure 3 This is a SEM image of the supported zinc-calcium composite product prepared in Example 2 of the present invention; Figure 4 The sulfidation curves of Examples 1-2 and the control sample ZnO997 tested in Test Example 1 of the present invention are shown. Detailed Implementation

[0057] The preparation method of the present invention will be further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are merely illustrative and explanatory of the present invention and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are covered within the scope of protection intended by the present invention.

[0058] Unless otherwise specified, the experimental methods used in the following examples are conventional methods; unless otherwise specified, the reagents and materials used in the following examples are commercially available.

[0059] Example 1 This embodiment provides a method for preparing a supported zinc-calcium composite using carbide slag and zinc oxide ore as raw materials, including the following steps: Step 1: Leaching. Take 82 g of calcium carbide slag (containing 90 wt% Ca(OH)₂ and 10-20 mesh particles) and 186 g of zinc oxide ore (containing 35 wt% ZnO and 10-20 mesh particles), mix them, and add 2500 mL of 1.6 mol / L NH₄Cl solution. Stir the solid-liquid mixture at 30 ºC for 3 hours to obtain a crude leaching slurry.

[0060] The second step is primary filtration. The crude leaching slurry is filtered to obtain a clarified leaching solution, in which Zn... 2+ The concentration is approximately 0.37 mol / L, Ca 2+ The concentration is approximately 0.39 mol / L.

[0061] The third step is to remove impurities. Add 3 g of zinc powder to the above leaching solution and stir at 50 ºC for 3 hours to obtain a refined slurry.

[0062] Step 4, secondary filtration. The above refined slurry is filtered to obtain a refined clear liquid, in which Zn... 2+ The concentration is approximately 0.38 mol / L, Ca 2+ The concentration is approximately 0.39 mol / L.

[0063] Step 5, pyrolysis and carbonization. Add 2.5 g of polyethylene glycol to the above purified liquid, stir thoroughly, and then continuously introduce a mixture of CO2 and air with a volume concentration of 10 vol% at a flow rate of 2.0 L / min for 8 hours under stirring conditions at 70 ºC. After completion, age for 30 min to obtain zinc-calcium precipitation precursor slurry.

[0064] Step 6, three filtrations. Filter the above zinc-calcium precipitate precursor slurry, and wash the filter cake thoroughly with deionized water until the filtrate is free of chloride ions to obtain the zinc-calcium precursor filter cake.

[0065] Step 7: Drying and calcination. The zinc-calcium precursor filter cake was dried at 100 ºC for 8 hours, then the dried filter cake was crushed into powder and placed in a muffle furnace, where it was slowly heated to 360 ºC and held at that temperature for 8 hours to obtain 145 g of supported zinc-calcium composite product 1. XRF analysis showed that the mass content of ZnO in product 1 was 35.8 wt%, and the mass content of CaCO3 was 63.6 wt%.

[0066] Example 2: Referring to the steps in Example 1, the difference is: In the first leaching step, 82 g of carbide slag (containing 90 wt% Ca(OH)₂ and 10-20 mesh particles) and 372 g of zinc oxide ore (containing 35 wt% ZnO and 10-20 mesh particles) were mixed and then 3500 mL of 1.6 mol / L NH₄Cl solution was added. The solid-liquid mixture was stirred at 30 ºC for 3 hours to obtain a crude leaching slurry. After filtration, the leaching solution contained ZnO. 2+ The concentration is approximately 0.55 mol / L, Ca 2+ The concentration is approximately 0.39 mol / L.

[0067] During the fifth step of pyrolysis and carbonization, the purified liquor (Zn) is added. 2+ The concentration is approximately 0.56 mol / L, Ca 2+ Add 2.5 g of polyethylene glycol to a solution with a concentration of approximately 0.39 mol / L. After thorough stirring, continuously introduce a mixture of CO2 and air with a volume concentration of 10 vol% at a flow rate of 2.0 L / min for 10 hours under stirring conditions at 70 ºC. After completion, age for 30 min to obtain a zinc-calcium precipitation precursor slurry.

[0068] 191 g of supported zinc-calcium composite product 2 was obtained. XRF analysis showed that the mass content of ZnO in product 2 was 62.9 wt%, and the mass content of CaCO3 was 37.2 wt%.

[0069] The physical properties of the supported zinc-calcium composite products prepared in the above embodiments are shown in Table 1.

[0070] Table 1. Physical property data of the supported zinc-calcium composite and ZnO997 prepared in the examples.

[0071] Note: The control sample was taken from commercial indirect zinc oxide, with a ZnO content of 99.7%, also known as ZnO997.

[0072] Test Example 1 The supported zinc-calcium composite prepared by this invention has high activity and can be used as a vulcanization aid in rubber vulcanization. A natural rubber formulation was used: 100 parts by weight of natural rubber NR, 30 parts by weight of carbon black N330, 1.5 parts by weight of antioxidant 4010NA, 2 parts by weight of stearic acid SA, 5 parts by weight of supported zinc-calcium composite or zinc oxide, 1.5 parts by weight of accelerator NS, and 1.5 parts by weight of vulcanizing agent S. The vulcanization properties of finished products 1 and 2 prepared in the above examples and commercial ZnO997 were investigated, and their vulcanization curves were tested.

[0073] Table 2. Sulfidation performance data of the supported zinc-calcium composites prepared in the examples and ZnO997.

[0074] As can be seen from Table 2 above, the sulfidation performance of the supported zinc-calcium composites prepared in Examples 1 and 2 is basically equivalent to that of ZnO997 prepared by the commercial indirect method. They can basically replace ZnO997, achieving the goals of high efficiency, zinc reduction, and cost reduction.

[0075] The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiments. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a supported zinc-calcium complex, wherein, The method includes the following steps: (1) Add ammonium chloride solution to the mixture of calcium carbide slag and zinc oxide ore, react, filter, and obtain zinc and calcium leaching solution; (2) Add zinc powder to the zinc and calcium leaching solution, react, filter, and obtain a refined zinc and calcium solution; (3) Add crystal form control agent to zinc and calcium refined clear liquid, then pass carbon dioxide gas flow, and at the same time pyrolyze and carbonize the mixed slurry, filter, dry, and obtain pyrolyze and carbonize products. (4) The pyrolysis carbonization products are roasted to prepare the supported zinc-calcium composite.

2. The preparation method according to claim 1, wherein, In step (1), the reaction temperature is 20-40℃; the reaction time is 2-12 hours; And / or, in step (1), the feeding ratio of the carbide slag and zinc oxide ore satisfies the following: the atomic ratio of zinc atoms to calcium atoms is 1:(0.5-3); And / or, in step (1), the feeding ratio of the carbide slag and the ammonium chloride solution satisfies the following: the molar ratio of calcium to ammonium chloride is 1:(3-8); And / or, in step (1), the concentration of the ammonium chloride solution is 1-5 mol / L.

3. The preparation method according to claim 1 or 2, wherein, In step (1), the zinc and calcium leaching solution includes Zn 2 + Ca 2+ and M j+ , j = 2 or 3, where M is other impurity metals that may be present in carbide slag and zinc oxide ore. Preferably, the zinc and calcium leaching solution comprises NH4Cl and [Zn(NH3)2]... i Cl2, MCl j [M(NH3)] i Cl j And CaCl2. Preferably, in step (1), the zinc and calcium leaching solution contains Zn 2+ The concentration is 0.2-1 mol / L; And / or, in step (1), the zinc and calcium leaching solution contains Ca 2+ The concentration is 0.2-1 mol / L; And / or, in step (1), in the zinc and calcium leaching solution, M j+ The concentration is 0.01-0.1 mol / L.

4. The preparation method according to any one of claims 1-3, wherein, In step (2), the reaction temperature is 30-50ºC; the reaction time is 1-6 hours. Preferably, in step (2), the zinc and calcium refined solution includes Zn 2+ Ca 2+ and M j+ , j = 2 or 3, where M is other impurity metals that may be present in carbide slag and zinc oxide ore. Preferably, the zinc and calcium purified solution comprises NH4Cl and [Zn(NH3)2] i Cl2, MCl j [M(NH3)] i Cl j And CaCl2. Preferably, in step (2), the zinc and calcium refined solution contains Zn 2+ The concentration is 0.2-1 mol / L; And / or, in step (2), in the zinc and calcium refined solution, Ca 2+ The concentration is 0.2-1 mol / L; And / or, in step (2), in the zinc and calcium refined solution, M j+ The concentration is 0.001-0.01 mol / L.

5. The preparation method according to any one of claims 1-4, wherein, In step (3), the crystal form control agent is selected from at least one of dodecyltrimethylammonium bromide, polyethylene glycol, and sodium polyacrylate; And / or, in step (3), the mass ratio of the crystal form control agent to carbide slag is 2-5:100; And / or, in step (3), the carbon dioxide gas flow is a mixture of carbon dioxide and air, wherein the volume concentration of carbon dioxide is 6-10 vol%. And / or, in step (3), the flow rate of the carbon dioxide gas stream introduced into each liter of zinc and calcium refined solution is 0.5-3 L / min; And / or, in step (3), the temperature of the pyrolysis carbonization treatment is 60-90ºC; the time of the pyrolysis carbonization treatment is 6-10 hours; And / or, in step (3), after the pyrolysis carbonization treatment is completed, the mixed slurry is filtered and the liquid component is collected. The liquid component contains a large amount of NH4Cl, which can be concentrated and treated to make a high-concentration ammonium chloride solution, which is then reused in step (1) as the leaching solution.

6. The preparation method according to any one of claims 1-5, wherein, In step (4), the roasting temperature is 300-500ºC; the roasting time is 4-10 hours. Preferably, in step (4), the gas released during the roasting process contains CO2, which can be captured or enriched to form a high-concentration mixture of carbon dioxide and air, and reused in the pyrolysis carbonization process of step (3).

7. The supported zinc-calcium composite prepared by the method according to any one of claims 1-6.

8. The supported zinc-calcium composite according to claim 7, wherein, The supported zinc-calcium composite comprises zinc oxide and calcium carbonate, with the zinc oxide coating the surface of the calcium carbonate. The supported zinc-calcium composite has a core-shell structure, with the core being calcium carbonate and the shell being zinc oxide. Preferably, the average particle size of the supported zinc-calcium composite is 200-600 nm; And / or, the specific surface area of ​​the supported zinc-calcium composite is 40-120 m². 2 / g; And / or, the thickness of the shell is 10-20 nm; And / or, the calcium carbonate accounts for 30-70 wt% of the total mass of the supported zinc-calcium complex; And / or, the zinc oxide accounts for 30-70 wt% of the total mass of the supported zinc-calcium complex.

9. The use of the supported zinc-calcium composite as a vulcanization aid in the field of rubber processing according to claim 7 or 8.

10. A rubber vulcanization method, the method comprising using the supported zinc-calcium composite of claim 7 or 8 as a vulcanization aid.

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